Abstract: The present invention discloses novel signaling pathways controlling the pathogenesis of the human respiratory bacterium, Haemophilus influenzae. The lipooligosaccharide-phosphorylycholine (LOS-PC) cell surface epitope of H. influenzae enhances pathogenesis but also increases bacterial susceptibility to innate and adaptive immunity and the administration of therapeutic compounds. Modulation of the LOS-PC epitope may be affected by an interaction between environmental conditions (i.e., for example, oxygen tension) and genetic regulation of precursor biosynthetic pathway activity. LOS-PC epitope display increases under microaerobic conditions and decreases under aerobic conditions. This is consisent with a bacteria's propensity to initiate pathogensis under low oxygen conditions. Pathogenesis may be prevented by disrupting the role of the putative H. influenzae homologue of CsrA, that downregulates galU expression. Disrupting CsrA repression of galU expression resulted in increased LOS-PC epitope display.

Abstract: Mariner-family transposable elements are active in a wide variety of organisms and are becoming increasingly important genetic tools in species lacking sophisticated genetics. The Himar1 element, a member of the mariner family, isolated from the horn fly, Haematobia irritans, is active in Escherichia coli when expressed appropriately. Using this fact, a genetic screen was devised to isolate hyperactive mutants of Himar1 transposase that enhance overall transposition from 4 to 50-fold as measured in an E. coli assay. These hyperactive Himar1 mutant transposases should enable sophisticated analysis of the biochemistry of mariner transposition and should improve efficiency of a variety of genetic manipulations involving transposition in vivo and in vitro such as random mutagenesis or transgenesis in a wide range of host cells than the transposable elements previously available.

Abstract: The invention features a general system for the identification of essential genes in organisms. This system is applicable to the discovery of novel target genes for antimicrobial compounds, as well as to the discovery of genes that enhance cell growth or viability.